Technical Field
The present invention relates to a prefilled syringe which, after previous storage and discharge of a drug solution in a syringe barrel, clearly indicates that the prefilled syringe has already been used.
Related Art
In order to prevent contamination of an injection drug solution caused by bacteria, and achieve simplified injection drug solution preparation, a drug solution is administered to a subject, for example, a patient using a prefilled syringe which previously stores a drug solution in a syringe barrel. In the prefilled syringe, a plunger which has a gasket in a tip region and a press portion in a base end region is inserted into the syringe barrel that stores the drug solution. Pressing the press portion allows the gasket to slide inside the syringe barrel, so that the drug solution is injected into the subject through an injection needle attached to a tip of the syringe barrel.
The amount of a drug solution of a bio-pharmaceutical such as an influenza vaccine to be administered to a subject is small, specifically, 1 mL or less. Further, when a drug solution is administered into the skin, the administration amount is extremely small, specifically, 0.5 mL or less. A prefilled syringe filled with such a small amount of drug solution has a syringe barrel having a small inner diameter corresponding to the drug solution amount, and the outer diameter of the syringe barrel thus becomes also small. Therefore, it is difficult for an operator, for example, a doctor to tightly hold the prefilled syringe during administration. As a prefilled syringe taking into consideration the above problem, WO 2011/122221 A1 discloses a drug administration device provided with a syringe barrel body which has a fluid chamber capable of accommodating a drug therein and a discharge section formed at the tip thereof, a plunger which is connected to a gasket slidably movable within the fluid chamber and has a shaft part of which is exposed outside from a tubular body, an outer barrel which is disposed outside the syringe barrel body and kept away from the tubular body, and a connection section which connects the syringe barrel body and the outer barrel. This drug administration device makes it possible to support and stabilize the outer barrel together with the syringe barrel body by tightly gripping the outer barrel with the entire palm, and to smoothly administer a drug solution.